Liquid filter drains are known for draining filter housings of accumulated contaminants. In diesel engines, for example, a fuel line filter is used to separate out water and debris. These contaminates accumulate in a lower portion of the filter housing.
For example, FIG. 1, which is taken from U.S. Pat. No. 8,157,997, the contents of which are incorporated by reference herein for all purposes in its entirety, illustrates a canister filter system 1 having a base 10, a canister 20, and a filter element 30. The general construction and use of a canister filter system is understood by those of ordinary skill in this art. Thus, all the details of the construction and use of canister filter system 1 need not be explained here. The canister filter system 1 may be used to filter fluids such as diesel or gasoline or other liquid fuels, lubrication oil, hydraulic fluid for hydraulic power systems, transmission fluid, or even possibly intake air for an engine. The canister filter system 1 may also be used as a fuel/water separator filter. The canister filter system 1 with the features described herein could be adapted by those of ordinary skill in this art to serve many different purposes and suit many other applications.
The base 10 includes an inlet channel 11 for fluid inlet into the canister filter system 1, and an outlet channel 12 for fluid outlet from the canister filter system 1. The base also includes base threads 13. Other attachment structure than threads may be used.
The canister 20 includes an open end 21 and a closed end 22. Adjacent the open end 21 are canister threads 23 which can be engaged with base threads 13 to hold the canister 20 to base 10. Threads are one example of engagement structures which may be included on the base 10 and canister 20 to form a releasable engagement. Other engagement structures may be used as will be recognized by those of ordinary skill in this art.
The filter element 30 may take many different forms to suit a particular application. In the illustrated embodiment, the filter element 30 is well suited for filtering fuel or lubrication oil. The filter element 30 may include annularly arranged filter media 31 circumferentially surrounding a central reservoir defined by center tube 32. Axial ends of filter media 31 are sealed by end plates. Open end plate 33 defines an axial open end of filter element 30. The open end plate 33 is termed “open” because it includes an opening 35 for allowing passage of fluid to outlet channel 12 from the central reservoir defined by center tube 32. Closed end plate 34 defines an axial closed end of filter element 30. The closed end plate 34 is termed “closed” because it prevents any fluid outside the filter element 30 adjacent axial end of filter media 31 from flowing unfiltered into center tube 32. Open end plate 33 and closed end plate 34 may each be joined to the center tube 32 via welding, adhesives, etc. Alternatively, several or all of center tube 32, open end plate 33, and closed end plate 34 may be constructed as unitary components.
Fluid to be filtered enters from the inlet channel 11 and flows to the annular cavity 28 between canister 20 and filter media 31. The fluid then passes into and through filter media 31, then into center tube 32 through the perforations shown therein in FIG. 1. The fluid exits center tube 32 through open end plate 33 and opening 35 into the outlet channel 12. The open end plate 33 and closed end plate 34 help define the fluid channels into and out of filter media 31, preventing any fluid from flowing directly to outlet channel 12 and bypassing filter media 31. First and second annular seals 38 and 39 may advantageously be included on filter element 30 and also help define and seal fluid passageways into and out of filter element 30. First annular seal 38 may be included on the open end plate 33 around opening 35 and adjacent the axial open end of filter element 30 to help seal the inlet channel 11 from the outlet channel 12. Second annular seal 39, larger in diameter than first annular seal 38, may be formed circumferentially around the open end plate 33 to provide the seal between canister 20 and base 10, or in other words provides a seal to prevent fluid in inlet channel 11 from leaking out of the joint between canister 20 and base 10. First and second annular seals 38, 39 may be integrally formed with open end plate 33, or attached with adhesives or other methods, as is known in this art. When first and second annular seals 38, 39 are integrally formed on or included on open end plate 33, proper replacement of these seals is assured when the filter element is replaced at proper intervals. Otherwise, a technician may fail to properly replace the seals at appropriate intervals, which could result in leakage out of the system, or leakage within the system allowing unfiltered fluid to bypass the filter element 31 and lead to contamination.
The filter element may have a generally cylindrical configuration that defines a longitudinal axis and a radial direction. Other configurations are possible.
A drain is typically disposed at the bottom of the filter housing and opened via some type of threaded connection. However, the filter assembly and filter line connected to the filter assembly is generally otherwise a closed system. Without a vent to replace outgoing fluid and contaminants with air, the contaminants either do not flow out of the housing or, if they do, they exit the drain inefficiently in spurts.
For example, FIG. 2 which is taken from U.S. Pat. Application Publication No. 2015/0202552, the contents of which are incorporated by reference herein for all purposes in its entirety, is a cross-sectional view taken axially through a filter housing assembly 100 with a drain valve assembly 102 in an open conformation, that is similar in nature to that disclosed in FIG. 1 although not exactly the same. The filter itself includes a porous filtering medium 150 and defines central chamber or space 152. As shown in FIG. 2, the drain valve assembly 102 is opened in response to the threaded stem portion 104 being unmated with the threaded filter portion 106. To open the drain valve assembly 102, the valve stem 104 may be rotated via a user or other service technician rotating a knob 108. The knob 108 is affixed to the valve stem 104.
Once the drain valve assembly 102 is opened, a series of passages for the release of fluid and the ingress of air are opened between the interior of the housing or canister 110 and the outside. These opening includes a drain outlet 112 disposed at the end of the second end 114. To facilitate collecting the fluid as well as an incidental amount of fuel, the drain outlet 112 includes a fitting 116 for a tube 118. In this regard, the filter housing assembly 100 is often disposed within the body of a machine and relatively close to the power source of the machine. In order to prevent fluid from the drain outlet 112 spilling into the machine or onto the power source, the tube 118 may be fitted to the fitting 116 and run to a desired location such as a waste receptacle. To help secure the tube 118 to the fitting 116, the fitting 116 may include one or more barbs 120 or other such structure such as ridges, grooves, or the like.
To continue, the body 122 has an axial passage 90 disposed therethrough. The axial passage 124 has a divider 126 disposed axially along at least a portion thereof. The divider 126 separates the axial passage 124 into an outlet passage 128 and a vent passage 130. In various examples, the divider 126 extends the entire length of the axial passage 124 or a portion of the length of the axial passage 124. In the particular example shown, the divider 126 extends a portion of the length of the axial passage 124 and stops at about the beginning of the fitting 116. However, in general, the divider 126 does extend past a vent side passage 132 the axial passage 124. This vent side passage 132 is configured to allow air into the vent passage 130 while reducing or preventing liquid from exiting out of the vent side passage. It is an advantage that this vent side passage 132 is distinct from the drain outlet 112 because fitting the tube 118 to the fitting 116 may otherwise reduce the ability of vent gases to travel back up through the drain outlet 112.
To continue, the outlet passage 128 is open at an inlet 134 disposed at the first end 136, at the drain outlet 112 and at a first side passage 138. The vent passage 130 is closed at the first end 136 in order to help direct the flow of vent gases into the housing 110 via a second side passage 140 as shown by a plurality of air flow arrows 142. The vent passage 130 is also open at the drain outlet 112 and the vent side passage 132. In operation, unscrewing the valve stem via the knob 108 unthreads the threaded stem portion 104 from the threaded filter portion 106. As the valve stem 104 moves downward or outward from the housing 110, the upper seal 144 is opened and the first and second side passages 138 and 140 are drawn down into the lower portion of the housing 110 where the fluid has collected.
Gravity works to urge the fluid into the first and second side passages 138 and 140 and a small vacuum pressure then draws air into the vent side passage 132, up the vent passage 130 and out the second side passage 140 to enter the housing 110 as shown by the air flow arrows 142. The replacement vent air then allows the fluid to continue flowing into the first side passage 138, down the outlet passage 128 and out the drain outlet 112 as shown by a plurality of fluid flow arrows 142. Of note, if vent gas is available to be drawn up from the drain outlet 112, this vent gas is drawn up along the vent passage 130 as shown by the air flow arrows 146. In addition, at all times and particularly near the end of the draining process, the second side passage 140 and vent passage 130 are available for draining fluid. This dual functionality of the vent passage 130 is self-regulated in response to the amount of vent gas needed to replace outgoing fluid and increases the efficiency with which the fluid exits the housing 110. While air is flowing into the housing, the liquid and its contaminants flow out of the housing. This flow is designated by arrows 148.
However, it has been found that the design of FIG. 3 still needs further improvement in order to break the vacuum to facilitate drainage. It should be noted that at no time does the space around the threaded portion of the stem 104 have substantial fluid communication with the interior of the housing as ledge 154 of the stem portion 104 never drops below the bottom end plate 156. This is prevented as the bottom ledge 158 of the drain assembly abuts the housing 110 first.
Other different ways of providing the necessary venting have been previously devised. One such example is the use of removable plugs at the top of the base of the filter assembly. However, this design has two drawbacks. First, this design does not allow for the efficient draining of higher viscosity liquids such as diesel fuel. Also, the drain time can be very slow as there is no way of breaking the vacuum when the liquid flows out of the closed system.
Another solution has been to add a vent plug to the filter base but this adds additional cost. In the field, maintenance technicians often loosen a fluid line that is attached to the filter base to provide venting. However, this may inadvertently lead to a technician forgetting to reattach the fuel line, which can result in a leak.
For all the above reasons, it is desirable to develop a better method for venting a filter housing than has been previously devised.